Combination multi-effect distillation and multi-stage flash evaporation system

Abstract

The combination multi-effect distillation and multi-stage flash evaporation system integrates a multi-stage flash (MSF) evaporation system with a multi-effect distillation (MED) system such that the flashing temperature range of the MSF process is shifted upward on the temperature scale, while the MED distillation process operates in the lower temperature range. The multi-stage flash evaporation system includes a plurality of flash evaporation/condensation stages, such that the multi-stage flash evaporation system receives a volume of seawater or brine from an external source and produces distilled water. The multi-effect distillation system includes a plurality of condensation/evaporation effects, such that the multi-effect distillation system receives concentrated brine from the multi-stage flash desalination system and produces distilled water.

I claim: 
     
         1 . A combination multi-effect distillation and multi-stage flash evaporation system, comprising:
 a multi-stage flash evaporation system comprising a plurality of flash evaporation/condensation stages, said multi-stage flash evaporation system receiving a volume of saltwater from an external source and producing distilled water; and   a multi-effect distillation system comprising a plurality of condensation/evaporation effects and a final condenser, said multi-effect distillation system receiving concentrated brine from said multi-stage flash evaporation system for further desalination thereof and producing a desalinated water distillate.   
     
     
         2 . The combination multi-effect distillation and multi-stage flash evaporation system as recited in  claim 1 , wherein each of the flash evaporation/condensation stages comprises a flash chamber and a condenser, the condenser having at least one conduit having an inlet and an outlet, the at least one conduit passing through the plurality of flash chambers. 
     
     
         3 . The combination multi-effect distillation and multi-stage flash evaporation system as recited in  claim 2 , further comprising means for extracting the volume of saltwater from the external source, passing it through the final condenser and feeding the volume of saltwater under pressure through the at least one conduit, the means being in fluid communication with the inlet of the at least one conduit. 
     
     
         4 . The combination multi-effect distillation and multi-stage flash evaporation system as recited in  claim 3 , further comprising means for heating the volume of saltwater after the volume of saltwater has been delivered through the at least one conduit and prior to injection thereof into the flashing stage. 
     
     
         5 . The combination multi-effect distillation and multi-stage flash evaporation system as recited in  claim 4 , further comprising means for extracting the distilled water from a last stage of the multi-stage flash evaporation system, wherein the heated volume of saltwater injected into the plurality of flash chambers is flashed into vapor within the plurality of flash chambers, and the vapor condenses on an external surface of the at least one conduit to form the distilled water. 
     
     
         6 . The combination multi-effect distillation and multi-stage flash evaporation system as recited in  claim 5 , wherein the means for extracting the volume of saltwater from an external source and feeding the volume of saltwater under pressure through the at least one conduit comprises at least one pump in fluid communication with the inlet of the at least one conduit. 
     
     
         7 . The combination multi-effect distillation and multi-stage flash evaporation system as recited in  claim 6 , wherein the means for heating the volume of saltwater comprises:
 a brine heater in fluid communication with the outlet of the at least one conduit; and   a boiler for delivering first heating steam into the brine heater after the volume of saltwater has been pre-heated by the at least one conduit.   
     
     
         8 . The combination multi-effect distillation and multi-stage flash evaporation system as recited in  claim 7 , further comprising a first desuperheater in communication with the heater for selectively cooling the first heating steam prior to delivery thereof into the brine heater, wherein a first portion of condensed steam produced by the heater is recycled for use in the first desuperheater and a second portion of the condensed steam produced by the heater is recycled for use in the boiler. 
     
     
         9 . The combination multi-effect distillation and multi-stage flash evaporation system as recited in  claim 8 , further comprising a second desuperheater for selectively cooling a second heating steam produced by the boiler prior to delivery thereof into a first one of the plurality of condensation/evaporation effects of said multi-effect distillation system. 
     
     
         10 . The combination multi-effect distillation and multi-stage flash evaporation system as recited in  claim 9 , further comprising:
 a plurality of feed heaters, wherein each said feed heater is in communication with the at least one conduit and a respective one of the effects; and   a plurality of flash pots, each flash pot being in communication with a respective effect and configured for pressure equalization.   
     
     
         11 . The combination multi-effect distillation and multi-stage flash evaporation system as recited in  claim 5 , further comprising a pre-treatment system for filtering the volume of saltwater prior to delivery thereof to said multi-stage flash evaporation system. 
     
     
         12 . The combination multi-effect distillation and multi-stage flash evaporation system as recited in  claim 11 , wherein the pre-treatment system comprises a nanofiltration membrane filter for removal of hardness ions from the saltwater. 
     
     
         13 . The combination multi-effect distillation and multi-stage flash evaporation system as recited in  claim 11 , wherein the pre-treatment system comprises a filtration system selected from the group consisting of a low pressure microfiltration system, an ultrafiltration membrane filtration system, and a combination thereof. 
     
     
         14 . The combination multi-effect distillation and multi-stage flash evaporation system as recited in  claim 11 , wherein the pretreatment system further comprises one or more valves to regulate the flow of the saltwater stream passing through the membrane filtration system and the remainder of the saltwater stream that is bypassing the membrane filtration system. 
     
     
         15 . The combination multi-effect distillation and multi-stage flash evaporation system as recited in  claim 5 , further comprising a pump in fluid communication with the at least one conduit and the inlet to the first one of the plurality of condensation/evaporation effects of the multi-effect distillation system, the pump being configured for extracting the remaining concentrated brine in the flash chamber of the last stage in the multi-stage flash evaporation and delivering it under pressure in two portions, wherein a first portion thereof circulates in the multi-stage flash evaporation system for further desalination, and a second portion thereof passes to the first effect of the multi-effect distillation system for further desalination. 
     
     
         16 . The combination multi-effect distillation and multi-stage flash evaporation system as recited in  claim 5 , further comprising a thermal vapor compressor in fluid communication with a final one of the plurality of condensation/evaporation effects of said multi-effect distillation system. 
     
     
         17 . The combination multi-effect distillation and multi-stage flash evaporation system as recited in  claim 5 , wherein the means for heating the volume of brine comprises:
 a brine heater in fluid communication with the outlet of the at least one conduit; and   a mechanical vapor compressor in fluid communication with at least one of the flash evaporation stages for delivering vapor generated in the last flash evaporation stage into the brine heater as first heating steam for heating the volume of brine after the volume of brine has been heated by the at least one conduit.   
     
     
         18 . The combination multi-effect distillation and multi-stage flash evaporation system as recited in  claim 17 , further comprising a desuperheater for selectively cooling the heating steam prior to delivery thereof into the brine heater. 
     
     
         19 . The combination multi-effect distillation and multi-stage flash evaporation system as recited in  claim 18 , wherein the desuperheater is in communication with the brine heater and at least a portion of condensed steam produced by the brine heater is recycled for use in the desuperheater. 
     
     
         20 . The combination multi-effect distillation and multi-stage flash evaporation system as recited in  claim 19 , further comprising a pre-treatment system for filtering the volume of saltwater prior to delivery thereof to said multi-stage flash evaporation system.